Safety device for centrifugal pumps



June 4, 1935. l. ARCHER 2,003,819

SAFETY DEVICE FOR CENTRIFUGAL PUMPS Filed April 22, 1955 TT RNEYPatented June 4, 1935 UNITED STATES 2,003,319 SAFETY DEVICE FORCENTRIFUGAL PUMPS Ira Archer, Brooklyn,- N. Y.

Application April 22, 1933, Serial NQLBGYAZG,

' 4 Claims.

This invention relates to a safety device for centrifugal pumps whosebearings are water- .lubricated, the type of bearing referred to beingone that must bealways submerged as is a the pump in order to preventthe bearing from burn ut. 7

Practically all vertical centrifugal pumps are supplied with waterlubricated bearings, that is, the hearing which is located in the casingof the pump next to the impeller is actually cooled and lubricated bythe water which the pump discharges, after drawing the same in. Severalefforts have been made, to lubricatethese bearings by grease orself-lubricating bearingv parts but in all instances, this has provenunsatisfactory because in grease bearings, the grease is washed out bythe flow ofthe Waterjand in self-lubricating substances, the samehardens when the water is not flowing and'when the 'pump continuesrunning, the bearing and the pump casing will over-heat when the pumpand its bearing are not covered with water with, the result that thebearing is burnt out and the pump is'destroyed. Up'to the present timeno I satisfactory, bearing except the water lubricated bearing has beenfeasible in vertical centrifugal pumps and inasmuch as the impeller willoperate against, the casing of the pump unless the pump itself iscovered with water, it is evident that when the level of the water dropsbelow the pump, there is great danger of the bearing burning out and thepump destroying itself if some means is not provided for shutting offthe motor when the water falls below a certain level.

In orderto shut off the motor use, has heretofore been made of floatcontrolled float switches but these switches operate to close thecircuit and start the motor when the water reaches a certain level butin many instances when the float falls, as the pump is operating, the,floatswitch b s n o en or t e float s l s i k h th tresultythat thewater is. pumped clear of the pump and its bearing and yet the motorcontinues to run. It is an object of my invention, therefore, to providean electric control which will operate to shut-01f the motor even.should the circuit be completed. by the float switch when the water hasfallen below the level of the pump, such .means contemplating use of apressure switch in the discharge line which maintains. the eircu' onlyas long as water is being pumped th ugh t e sc a e l nei r Chan es and via io s m b ma in the construction shown and described withoutdepartingfrom the principles of the invention or (Cl. 103,26) i K sacrificing itshief l a t g sihehees f" vention is not to'be confined-to the structuresshown in the accompanying drawing, in which;

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Figure 1 is a diagrammatic viewshowing he arrangement of; the partsemployed inflsafe d n a c i u P m h t i bmer d for normalop'eration, andt A Figure 2 is a view inuelevation of the float rod upon h n rg nc fl aan i swihh are supported. 7 t, j 1 "Z Referring to t e drawin in detail.fiiinqieetes the top or roof of a sump 6 in whichis supported, as at I,the centrifugal pump 8, the water level e n indicaiedrby h n me al a idii a la ns a Th umni a r nged ail "t a e rou a d se a sel eef H hi nds inhe exter o of he siii l r ch mb v t, I it T e Pu p 8, being i he' eri aeeeiri i a type, is r id l he Pu p-51 w 'li'ith eh t n s thr u -and isper ed by, ih' mqt r I2, the motorbeing supportedjon said' roofer top 5of the chamber 6, o V

Use is made of a float M which gedfto have free l di movemen Qn EflMQ'FQdQIF' between the points lfi'and 'l! and normally when the float isinv theiposition illustratedfin 1, the motor shouldlnotf be, o eratedand the, float switch l8 should be open, When" than at M moves up underthe influence qiitlie rise-of water in the chamber fi'and'reaches the,point l1, it moves withgit the float rod I 5 to close the fl w It thu cmp etin a 'cire itl' ug the wire l9 and wire 2|, to energize the coilare definite time relay 2,2. 'I,' hisdefinite tinieirelay is of e ln chn a r c nstruction nd is delayed in its movementb y a dash po't 23hrother similar construction so that the contact nd 24 of t e re w l breakt i cu t a tli ,c wi 2 4 a t a predetermined 9 min???- val. When thefloat switch I8 is closed, a cu;- ..rent path is closedthrough the line.[9, to enerze h m t circuit @01 2 he ol iQ' c re "o w i m to lo th m tcircuit 9 and start the motor I 2 which inturnvoperates hfi Pump 8 tolower the water in the charnber .6.

The circuit of coil.28 is completed through lines 21, 3|; contact piece24 of the time relay, ,and contacts25 and 26 which arein circuitwithlines 3i and 32, the latter of whichis connected, to line 2|,permitting the current to ,returnto the negative side of the power line33- A. Simultaneously, the current passes through line 2] and the timerelay 22 is energized and the retarded core thereof begins to move thecontact 24 The pump, however, having begun to operate, builds uppressure in the discharge line H and causes the pressure switch to moveaway from the contacts 34, 35 and into engagement with contacts 36 and31. After contacts 36 and 31 are bridged, the contact portion 24 in itstimed operation breaks the circuit through 25 and 26 but the motorcontinues to operate because the current through motor circuit coil 28passes through line 3|, contacts 36 and 31, lines 32 and 2| and back toline 33-A. The pump will lower the water in the pit or chamber 6 and ifthe operation of the self-closing switch I8 is normal, it will open whenthe weight of the float I4 is on the stop IS on the float rod l5, andbreak the control circuit and consequently the motor circuit;

When the switch l8 does'not open, however, there is danger of ruiningnot only the pump bearings but the pump itself and when the waterpressure in the line H falls, the pressure switch 33 will leave thecontacts 36 and 31 thus breaking the motor coil circuit and causingseparation of the motor circuit contacts38 and-39 and stoppage of themotor.

While the switch I8 is closed, the time relay 22 remains energized andkeeps the contacts 40 and 4| bridged to complete an alarm circuitincluding the line 42in which are disposed audible and visible alarmelements in the nature of a lamp 43 and a bell, throughcontacts 34 and55; line 32 and line 2| to the power circuit 33-A, so that an attendantmay be summoned to correct the trouble.

The pump will hence remaininoperativeuntil .the water again rises towhat might be termed a maximum or dangerous level as indicated by theoutline 45. Referring to Figure 2, the auxiliary or emergency float andfloat switch are illustrated as consisting of an emergency float freelyslidable on the float rod l5 and supported on the adjustable ring 5|,said float having an extended collar portion 52 which, when the float 50rises, lifts thespool 53 off its adjustable support ring 54 to advancethe spool so that its upper face contact strips 55 which are connectedby a coil 56, for quenching an arc, engage the contacts 51 secured inflbre'disc 58 to complete a circuit in the line 59 (see Figure 1). The

disc 58 is stationary, i.-e., with regard to float 50 and spool 53. Itis secured to rod I5 and moves with it.

when the water raises the float 50 to close the circuit in line 59, themotor circuit coilis energized and closes the motor circuit as the line21 is also connected to'line 59. The operation of the motor thuskeepsthe water from overflowing the pit or chamber 6 until an attendantrestores the mechanism'to normal operation by opening the switch l8.-The alarm system is in operation because line 42 completes a circuitthrough line 59.

It-is evident,- therefore, that I have provided a device which hasseveral advantages, first; it prevents the pump from running dry whichis detrimental because in a vertical centrifugal pump during discharge,water sustains the impeller in a central position in the pump casing andprevents it from destroying the pump casing which it will do whenoperating without water and second; the pump can be tested in inspectionoperation for a few seconds without being completely submerged, theoperation ceasing upon movement of the time relay; and third; the motorwill not continue to operate when the pressure in the line I I drops,thus assuring the coverage at i of a circuit for said motor, a float andfloat rod inthe chamber operable by a rise of water to close aself-opening float switch, a control circuit for said motor circuitincluding said selfopening float switch and a motor circuit maintainingmember, a time relay for breaking the control circuit at a predeterminedtime, a switch operable by the water pressure in the discharge pipe forcompleting said control circuit before the same is broken by saidrelay,and an auxiliary float and float operated means for completing saidcontrol circuit upon an abnormal rise of water in the chamber.

2. The combination with a motor operated centrifugal pump and dischargepipe for maintaining water in a chamber at a minimum level, of a circuitfor said motor, a float and float rod in the chamber operable by a riseof water to close a self-opening float switch, a control circuit forsaid motor circuit including said self-opening float switch and a motorcircuit maintaining member, a time relay for breaking the controlcircuit at a predetermined time, a switch operable by normal waterpressure in the discharge pipe for completingsaid control circuit beforethe same is broken by said relay, a 'signal circuit bridged by said timerelay when the control circuit is broken thereby, said pressure switchforming a part of said signal circuit when the water pressure in thedischarge pipe drops below nor- .mal, an auxiliary float and floatoperated means for completing said control circuit upon an abnormal riseof water in the chamber, and asignal in said signal circuit arranged tooperate when the signal circuit is completed by failure of the floatswitch to open.

3. The combination with a motor operated centrifugal pump and dischargepipe for maintaining water in a chamber at a minimum level, of a circuitfor said motor, a float and float rod in the chamber operable by a riseof water to close a self-opening float switch, a control circuit forsaid motor circuit including said self-opening float switch and a motorcircuit maintaining when the float switch fails to open, an emergencycircuit including said motor circuit maintaining solenoid, the firstmentioned float switch and an emergency float switch, and an emergencyfloat for closing said emergency switch to render the motor circuitmaintaining solenoid effective.

4. The combination with a motor operated centrifugal pump and dischargepipe for maintaining water in a chamber at a minimum level, of a circuitfor said motor, a float and a float rod in the chamber operable by arise of water to l close a self opening float switch, a control circuitfor said motor circuit including said self opening float switch and amotor circuit maintaining solenoid, a time relay for breaking thecontrol circuit, a pressure switch for maintaining the control circuitcomplete when pressure is present in the discharge pipe and after saidcontrol circuit is broken by the time relay, said pressure switchoperating upon a fall in pressure in the pipe to open said controlcircuit and render said motor circuit maintaining solenoid ineffectivewhen the float switch fails to open, an emergency circuit including saidmotor circuit maintaining solenoid, the first mentioned self openingfloat switch and an emergency float switch, an emergency float forclosing said emergency switch to render the motor circuit maintainingsolenoid efiective, and an alarm signal circuit connected to the controland emergency circuits and arranged to be maintained closed by the timerelay and the pressure switch when no pressure is present in saiddischarge line and the first mentioned float switch has failed to open,and by said time relay and the emergency float switch when said firstmentioned float switch has not opened and said emergency float switchhas been closed.

IRA ARCHER. [L.s.]

